Aim 4. The pilot study will be to conduct a proof of concept add-on treatment study of the antibiotic minocycline for bipolar patients who are depressed, likely to be obese and likely to have elevated inflammatory markers and increased risk of heart disease. This is a proposal to conduct a 2-site trial of 50 subjects to examine the value of minocycline augmentation in bipolar depressed patients who are incompletely responsive to initial treatment with anti depressants and/or mood stabilizers. The investigators will compare two subgroups of depressed patients, those who have high (N=25) versus those who have low (N=25) levels of C-reactive protein (CRP) as defined below.